Air processors include evaporative air coolers and humidifiers. Evaporative air coolers can provide a cost-effective alternative to air conditioners in a number of situations. One type of portable evaporative cooling unit is disclosed by Calvert in U.S. Pat. No. 5,606,868. Enclosures for air coolers is disclosed by Calvert in U.S. Pat. No. 6,223,548 and by Wulf and Calvert in U.S. Design Pat. 362,905, for example.
Currently, many varieties of evaporative air coolers exist in the market place. Generally, they are classifiable into (a) residential and light commercial-type coolers, and (b) industrial and heavy commercial-type coolers.
Most residential and light commercial air coolers typically use injection molded plastic as the material of the enclosure. Injection molded plastic offers an advantage of good aesthetics, several combinations of design options, and mass production capabilities. Most residential air coolers have poor cooling performance, and deliver low pressure air.
Industrial and heavy commercial-type coolers, on the other hand, are characterized by a rugged construction and high levels of cooling performance and delivery of high pressure air. Industrial and heavy commercial-type coolers are generally outdoor use capable, and much bigger in sizes as compared to residential air coolers.
To achieve ruggedness and strength for large size enclosures, industrial air cooler housing are generally made from metal, typically steel sheet, aluminum, or stainless steel. Some cooler varieties are also available with enclosures made in tough plastic materials constructed using rotation or “roto” molding, resin transfer, or FRP (fiber-reinforced polymer) technology. Some cooler varieties make use of injection molding for some components like front aesthetic grill, louvers etc. Very few air coolers use injection molding for a complete housing and, then, only for their small-size models. For larger-size models, they revert to metal or roto-molded enclosures.
Metal enclosures have disadvantages including: (a) lower productivities; (b) prone to rust and corrosion; (c) dimensional accuracies not achievable in close tolerances; (d) higher costs; (e) distortion in shape over a period of use; and (f) increased weight, causing difficulties in portability, and higher transportation and carriage costs.
Roto molded, FRP molded, or resin transfer molded enclosures have disadvantages including: (a) extremely lower productivities; (b) high levels of dimensional variation from piece to piece; (c) generally surface finishes are not very good or appealing; (d) usually needs secondary finishing operations after primary molding processes; (e) strength variation from piece to piece, i.e., process control is more challenging; and (f) generally higher weights than injection or blow molding.
Injection molded enclosures have disadvantages including: (a) molds are expensive; (b) moving cores required for undercuts and special shapes; (c) generally hollow articles not possible unless gas assisted injection molding is employed; (d) lower strengths as compared to roto or blow molding; (e) runners, sprue, gates, and, flashes are difficult to be 100% reused in new components; and (f) not all injection molding material grades are suitable for outdoor use. Also, the materials which are suitable for outdoor use need UV and other additives to be added to achieve proper outdoor capabilities.
It is therefore desirable to have enclosures with more advantages and fewer disadvantages.